Python Real-Time Chat Application

A robust, multi-threaded client-server chat application built using Python. Originally a simple CLI tool, this project has been upgraded to feature a modern graphical user interface (GUI), secure user authentication, and a custom JSON-based TCP networking protocol.

Features

• Graphical User Interface: A clean, dark-themed UI built with PyQt6, featuring separate tabs for different conversations.
• Secure Authentication: User registration and login functionality backed by a local SQLite database and bcrypt password hashing.
• Group & Private Messaging: Support for global channels (e.g., #General, #Coders, #Gamers) as well as one-on-one direct messaging (DMs).
• Real-Time Online Roster: A live-updating sidebar displaying currently connected users.
• Robust TCP Networking: Custom buffer management using newline-delimited JSON to safely handle fragmented or "sticky" network packets.
• Multi-Threading: Allows the server to handle multiple clients concurrently without blocking.

Prerequisites & Setup

• Python 3.12 or 3.13 (Note: Python 3.14+ may require manual C++ compilation for the PyQt6 library, so 3.12/3.13 is highly recommended).

It is recommended to use a virtual environment to install the dependencies (PyQt6 and bcrypt).

1. Create a virtual environment:

   python -m venv .venv

   (Windows users can also use the launcher: py -3.13 -m venv .venv)

2. Activate the virtual environment:

   • Windows:

     .venv\Scripts\activate

   • macOS/Linux:

     source .venv/bin/activate

3. Install the required libraries:

   pip install -r requirements.txt

How to Run (Local Machine)

1. Start the Server: Open a terminal, activate your virtual environment, and run the server. (On the first run, it will automatically generate the chat_users.db database).

   python server.py

   You should see a message indicating the server is listening on 0.0.0.0:65432.

2. Start the Client: Open a separate terminal window, activate the virtual environment, and launch the GUI client:

   python gui_client.py

3. Connect and Authenticate:

   • In the client window, enter 127.0.0.1 and click Connect.
   • The server will prompt you in the chat box to type 1 to Login or 2 to Register. Type your response directly into the message input field and press Send.

How to Run (Local Network)

1. Start the Server: Run server.py on your host machine. Make sure the host IP in the script is set to 0.0.0.0 to accept external connections.
2. Start the Client: On a different machine on the same network, open gui_client.py.
3. Connect: Instead of 127.0.0.1, enter the local IPv4 address of the host machine (found using ipconfig on Windows or ifconfig on macOS/Linux).

How to Run (Using Executables)

If you do not want to set up Python, you can use the standalone executables:

1. Navigate to the dist/ folder.
2. Run server.exe on the host machine.
3. Distribute and run ChatClient.exe on client machines, entering the host's IPv4 address to connect.

Project Structure

• server.py - Central server handling connections, routing, and user sessions.
• gui_client.py - Main application executable containing the PyQt6 interface.
• client_core.py - Networking backend handling socket transmission and buffering.
• db_manager.py - Database handler for chat_users.db and credential verification.
• requirements.txt - Project dependencies.

Technologies Used

• Language: Python 3
• Libraries: socket, threading, json, sqlite3 (Standard), PyQt6, bcrypt (Third-party)
• Protocol: TCP/IP